"Giving the benefit of the doubt makes me a doormat"

Here's the fear that keeps the habit going even in people who can see it's mostly wrong. If I stop charging, I'll let everything go. People will walk over me. The interrupter will keep interrupting, the friend will keep not replying, and I'll be the one who smiles and takes it.

This confuses two separate things, the motive and the act. You can object to an act without deciding the motive. In fact you can only object well when you haven't decided the motive, because an objection that comes packaged with a verdict gets argued about at the verdict end. Say "you talked over me because you don't take me seriously" and the reply is "that's not true", and now you're arguing about their character, and the interruption has vanished. Say "I hadn't finished, can I pick that up" and there's nothing to argue with. The act gets addressed. The motive never needed deciding.

An earlier book, You don't have to win this one, is about the row over who's right. This is the row upstream of that one, the row about what they meant, and the way to avoid it is to notice you never have to have it. Dropping the charge isn't dropping the objection. It's dropping the part of the objection that can't be checked and can only be fought about. What's left is the part that can be fixed.

So what does a person who's stopped charging look like, from outside? Not a doormat. Someone who says, on the day, "that stung, I don't think you meant it, but I wanted you to know" and then moves on. Someone who, when a colleague repeatedly interrupts, says in the moment "hang on, I'll finish this", every time, without heat, because there's no charge behind it to generate heat. That person is harder to walk over than the one who's seething and saying nothing, because they're actually objecting, out loud, to the actual thing. Charging and objecting aren't the same. The habit usually delivers the first and skips the second, which is the doormat outcome it was afraid of, arrived at from the other direction.